The present work describes the analysis of carbo-nitride precipitation kinetics in tempered martensite of Nb–Ti-microalloyed steel with a carbon content of 0.3 wt%. Based on the information obtained from transmission electron microscopy and scanning electron microscopy, a computational simulation procedure is developed within the software package MatCalc, which is capable of describing the experimental results in terms of the number density, composition, and type of precipitate phases. No explicit fitting parameters are used in the computer simulation. The input data is entirely based on independent physical or microstructural parameters. To determine the chemical composition and type of precipitates, energy dispersive X-ray spectroscopy and selected area electron diffraction are utilized. The simulation results and the experimentally obtained information are in good agreement.